How to uncheck the hide field if it is grayed out?

Hi,

I have added a field in the datasource definition by changing FM logic and adding extra field in extract structure for generic extraction.

The check box is checked in the hide column against the newly added field in RSA6 transsaction for the datasource and it is grayed out!

how to uncheck that check box? i don't want that field to be hidden!

Thanks,

Ravi